For replacement parts of a photoreceptor drum, a transfer belt, a toner cartridge and the like which are used for an image forming apparatus such as a multi-functional peripheral, a distributor of a device provides genuine supplies thereof for assuring print quality, while a third party other than the distributor has been increasingly selling supplies as interchangeable parts. The interchangeable parts are inexpensively supplied, whose print quality is however not assured at all, and a seller of the interchangeable parts has not been responsible for maintenance of equipment under the current circumstances. Further, the image forming apparatus itself is not designed to support even nongenuine supplies. Thus, in the case of using a nongenuine product, blur, fog and the like of printing are notably caused under environmental conditions such as high temperature, high humidity, low temperature, low humidity and the like, thus reducing print quality.
For example, when a nongenuine product of a toner is used in the image forming apparatus, since toner characteristics and setting of development bias are insufficient, there is a case where the amount of toner attached to the photoreceptor drum becomes large to cause fog on recording paper. Moreover, conversely, when the amount of toner attached to the photoreceptor drum is small, blur is caused on recording paper.
Further, when the nongenuine toner is not adapted to setting of an apparatus of the image forming apparatus, there is a case where a toner transferred on recording paper is not fused fully at a fixing portion and the toner is not fixed on the recording paper or a case where it is fused too much at the fixing portion and characters are collapsed. When the toner characteristics and heating temperature of the fixing portion are inappropriate like this, in both cases, adverse effect is given on a printed image, such as that the toner is attached to a heat roller to thereby contaminate recording paper for which printing is performed next time, or that the toner is attached to the side of a pressurizing roller to thereby contaminate front and back sides of recording paper. In particular, as temperature and humidity becomes higher, image density becomes higher and fog is caused more easily, and as a printing rate becomes higher, an incidence rate of fog also tends to be increased.
For such a problem, for example, Patent Document 1 describes an image forming apparatus recognizable whether or not a replacement part is a genuine product. In such an image forming apparatus, manufacturer name information of a toner is read from a memory tag incorporated in a toner cartridge to compare the read company name information to company name information stored in advance, and determination is made, in the case of match, that a mounted toner cartridge is a genuine product to display the company name information on a display portion, followed by execution of image density correction action, while determination is made, in the case of mismatch, that the mounted toner cartridge is a nongenuine product not to display the company name information on the display portion, as well as displaying that the image density correction action is not executed.
Additionally, Patent Document 2 describes an image forming apparatus capable of selecting a first mode assuming use of genuine consumables and a second mode permitting use of nongenuine consumables. Such an image forming apparatus is comprised of consumables judgment means for judging whether mounted consumables are genuine or nongenuine, and print job receiving means for receiving a print instruction, in which, when the first mode is selected, in a case where consumables to be used in order to reproduce a color instructed for printing in the print job receiving means includes consumables judged as nongenuine by the consumables judgment means, the consumables judged as nongenuine is not used, and only the consumables judged as genuine is used to form an image.